Cut a 1.6 60' and spun the crank hub last night. Would have been a good run.

That was the end of the @maximumpsi 9 second chase and the F80 M3 and F82 M4 community have been holding their collective breaths since for a solution to the crank hub spinning problem. Maximum PSI has yet to comment on what they intend to do to BimmerBoost.

What is the cause? It is somewhat difficult to pin down but look at this comparison of the S55 3.0 liter I6 crankshaft and the E9X M3 S65 V8 crankshaft:

The S65 crankshaft is on the right and you can see timing gear and oil pump gear are a part of the design whereas the S55 does not have the same design. The S55 quite frankly is simply an evolution of the N54/N55 geometry and design which is basically the same. That makes one wonder why the N54 and N55 do not see this problem to the same degree. Is it the higher redline of the S55 that is partially to blame?

Perhaps. You can say what you want about the BMW turbo era and it's easy power with bolt ons but the fact is if BMW raced the S55 design the same way they raced the S65 design no doubt this design flaw would have popped up in serious Motorsport competition and it would have been addressed before production.

It is not some fluke. Here is what BimmerBoost member @sA x sKy had to say about it and his own experience:

Originally Posted by sA x sKy

It's happened to me 4 times. First time dealer warrantied it. The other 3 times I paid out of pocket and repair costs total is like $6000.

It's suspected that due to road vibrations, the crank hub bolt gets loose over time and eventually causes the crank hub to spin on the crank and the car goes out of time. Every single time it happened to me was when I hit the kick down button during a pull on the highway.

BMW doesn't key the hub from the factory.

The problem has happened to stock cars as well. In my case, the bolt didn't have loctite on it, so maybe that should help this time around. If it happens again, I'm turning the car back to stock.

TPG Tuning supposedly has a solution but @JasonTPG has yet to tell us anything about it. Their idea was to cut a notch in the stock piece but it didn't work and they are trying a different approach now:

Yea those are both my hubs. Unfortunately the TPG hub failed on me 3 times and they broke the same way each time with a piece of the sprocket coming off. I have their one piece hub but I am debating whether to use it or not because it requires some modification of the chain guard.

So what else can one try to prevent this? Well, Gintani thinks they have the solution:

Originally Posted by Gintani

Hi we are looking for a #f8x#m4 or #m3 to test fit our one piece crank hub and upgraded bolt for final production. We need a car that is local to us since we no longer have ours. We are offering all labor for free and a discounted price on hardware all other details will be discussed later.

They are looking for someone to test this out. Speaking as someone who has had Gintani try various solutions with on his own car for going on six years now a word of advice is to not be anyone's guinea pig and let them try their solutions out on their own cars first. Let them assume the risk considering their track record and pay for their own development.

Will the Gintani one piece crank hub solve this issue? Who knows. Maybe there just is no solution:

Originally Posted by Maltman

BMW saw this issue first time on an engine test bed long time before the first vehicle was delivered. The same issue is known from a 4 cyl engine - same parts/system.

The real problem is not the hub (2) or the wheels (5). Itīs the bolt (3), which holds the wheel and crank hub. The bolt dissolves because of vibrations coming from the vibration damper (1) in front of it - or from any other imbalanced source. If it dissolves, your chain wheel spins and timings adjusts.

So why not just tighten the bolt, or make the hub and wheels from one piece? Because this system works like a fuse. This "fuse" protects your crankshaft against imbalanced parts and vibrations. If you fix the bolt (weld etc), it can't come loose and you risk damages to your crankshaft and bearings etc. The "solutions" some tuners offer are very dangerous, BMW constructed everything for a reason. Example? You can't (or its very difficult) set timings with a fixed wheel. We spoke honestly with the engineer, about solutions, whats possible. The reality is: there's no solution. You can fix the bolt but you open a range of new risks. You can install a one piece hub/wheel - and of this the engineer urgently advised against - you risk even more damages.

JoeFromPA is right - there are over 40k vehicles and just round about 40 (BMW said this) known cases, most of them with only wrong timings. You even can't check the bolt, only thing you can do is change the bolt every year or every xxxxx miles/km. The bolt is tightened with 200 Nm and 2x 260 degrees

The Gintani solution may introduce new problems. BMW seems to be aware of the issue but they still put the car in production. It's a numbers game for them. How many cars can they sell and what % will have the issue? Apparently the number is low enough to simply pay out warranty claims on those cars that spin their crank hub (and have not been tuned).

You can have your bolt replaced and tightened every so often which is probably the best way to go. Maybe someone will come up with someone else. Maybe not. Where we are at right now is BMW quite simply screwed up on the S55 design and doesn't care.

BimmerBoost reached out to BMW for comment on the issue but do not hold your breath for a response.

It's happened to me 4 times. First time dealer warrantied it. The other 3 times I paid out of pocket and repair costs total is like $6000.

It's suspected that due to road vibrations, the crank hub bolt gets loose over time and eventually causes the crank hub to spin on the crank and the car goes out of time. Every single time it happened to me was when I hit the kick down button during a pull on the highway.

BMW doesn't key the hub from the factory.

The problem has happened to stock cars as well. In my case, the bolt didn't have loctite on it, so maybe that should help this time around. If it happens again, I'm turning the car back to stock and turning the the lease in lol.

This sounds like a pretty big problem. Is loctite the solution or is it more of a design defect? How do you address this?

It's happened to me 4 times. First time dealer warrantied it. The other 3 times I paid out of pocket and repair costs total is like $6000.

It's suspected that due to road vibrations, the crank hub bolt gets loose over time and eventually causes the crank hub to spin on the crank and the car goes out of time. Every single time it happened to me was when I hit the kick down button during a pull on the highway.

BMW doesn't key the hub from the factory.

The problem has happened to stock cars as well. In my case, the bolt didn't have loctite on it, so maybe that should help this time around. If it happens again, I'm turning the car back to stock

NOOOO! I'm patiently waiting to see you snap those TPG axles! Don't give up yet.

Plan was to buy it out. I didn't really know I was gonna go down this road. My lease deal with incentives and because of the fleet program came out ahead vs financing the car. More money in my pocket meant more money to spend on mods. I leased my 335 as well and ended up buying it out which is what I've been driving while the M4 is down. I plan on doing the same assuming the crank hub doesn't $#@! me over again.

Plan was to buy it out. I didn't really know I was gonna go down this road. My lease deal with incentives and because of the fleet program came out ahead vs financing the car. More money in my pocket meant more money to spend on mods. I leased my 335 as well and ended up buying it out which is what I've been driving while the M4 is down. I plan on doing the same assuming the crank hub doesn't $#@! me over again.

Look, whatever, that is your business. I personally don't care what you do with your money or car.

What I want to know is more about this crank hub issue and how to fix it. Additionally, how many people are affected and if there is anything that exacerbates it.

Look, whatever, that is your business. I personally don't care what you do with your money or car.

What I want to know is more about this crank hub issue and how to fix it. Additionally, how many people are affected and if there is anything that exacerbates it.

I was just answering what someone else asked. Either way I told you what the only solution is. There's a picture Jason sent me awhile ago comparing the S55 crank vs an S65 crank. I'll see if I can find it.

This is worse than the rod bearing problem because this problem can happen at any time and is very unpredictable. It failed on Jesse@PURE too way back but I believed the dealer just replaced his crank bolt.

Here's a picture. Notice how the timing gear and oil pump drive gear are actually part of the crankshaft on the S65 vs the $#@!ty S55 design. Apparently it's like this on the N54/N55 motors as well. BMW really went out of their way to cost cut this motor.

Notice how the timing gear and oil pump drive gear are actually part of the crankshaft on the S65 vs the $#@!ty S55 design. Apparently it's like this on the N54/N55 motors as well. BMW really went out of their way to cost cut this motor.

Because the gear is part of the crank as I understand it. I left my crank bolt attached when I removed the crank, so I didn't verify.

Originally Posted by sA x sKy

Here's a picture. Notice how the timing gear and oil pump drive gear are actually part of the crankshaft on the S65 vs the $#@!ty S55 design. Apparently it's like this on the N54/N55 motors as well. BMW really went out of their way to cost cut this motor.

The camshaft gears are the same way. I don't know why BMW doesn't use keys for the camshafts and crank for timing. Every motor I've assembled (Japanese) has these which makes timing simple and makes this failure impossible.

OP, I would look into welding it on there. I can't think of any con. The only con is you can't easily replace the cog (would require machining), but it should never be damaged.